Study On The Preparation And Performance Of PTFE Foam Coating Glass Fiber Composite Filter Material

In order to protect the ecological environment and reduce air pollution,the Chinese government has increased its environmental protection efforts.Driven by a series of environmental protection policies,my country’s overall air quality has continued to improve,and the development of energy-saving and environmental protection industries has accelerated.The main cause of air pollution is the emission of industrial smoke and waste gas.Reducing or preventing the emission of particulate matter in industrial smoke and dust is one of the effective means to reduce air pollution.The bag filter is widely used as the main dust removal equipment in the process,and the performance of the filter material determines the use effect of the bag filter.Therefore,in the face of increasingly strict environmental protection policies,it is necessary to develop a high-performance high-temperature-resistant filter material in order to create a better living environment.Polytetrafluoroethylene(PTFE)has strong high temperature resistance and chemical resistance,low friction coefficient,easy dust removal,and strong hydrophobicity.Glass fiber woven fabric is resistant to high temperature,corrosion,high tensile breaking strength and good dimensional stability.PTFE microporous membrane composite glass fiber woven fabric is one of the preferred materials for ultra-low emission of industrial smoke and dust,but the PTFE membrane filter material has the disadvantages of easy damage and poor membrane fastness.Therefore,this project takes PTFE emulsion as the main solution,glass fiber woven cloth as the base cloth,and adopts the technology of finishing after foam coating to prepare a new type of PTFE foam coating glass fiber composite filter material,to make up for the shortcomings of PTFE coating filter material,which is applied to high-temperature industrial dust removal bag filter field.The basic formula of PTFE emulsion foam is determined by studying the foaming formula system of PTFE emulsion.By comparing three different foaming methods,the best foaming method is selected,and the characteristics,stability and structure of high-speed foaming are studied.PTFE foaming solution rich in foam is scraped and coated on glass fiber woven cloth by scraper coating method.The temperature and time parameters of heat treatment are changed,and the optimum technological parameters are selected to study the mechanism of micropore structure formation.Finally,the specific process of preparing PTFE foam coating glass fiber composite filter material is obtained,and a series of performance tests and analysis are carried out on PTFE foam coating glass fiber composite filter material.Through the exploration of PTFE emulsion foaming formula system,1% betaine is added into PTFE emulsion as foaming agent,2% Twine 80 as foam stabilizing agent,1% methyl cellulose and 3% acrylic resin as thickening agent.PTFE foaming solution rich in foam can be prepared by using the high-speed multi-dimensional stirring bar method.The foam ratio is 8.46,the density is 0.25g/m L,the bubble diameter is 0.1-0.5mm,the foam is in a very stable state within 30 min,and the original bubble pore structure can still be maintained under the drying state.PTFE foam coating is applied to the surface of glass fiber woven cloth with scraper coating,and it undergoes three stages of heat treatment: low-temperature drying at 160℃ for 5min,high-temperature sintering at 360℃ for 10 min,and slow cooling treatment for 5h.During low temperature drying,water evaporates from the surface of the coating,the foam shrinks and the bubbles visible in the coating disappear.Under the effect of high-temperature sintering,other additives and impurities are decomposed and removed,and PTFE particles begin to shrink,melt and agglomerate,which forms a coating structure with a large number of micropores.Finally,PTFE foam coating glass fiber composite filter material with excellent performance was prepared.The PTFE foam coated glass fiber composite filter material has excellent mechanical properties and retains the original excellent properties of glass fiber.It can be used for a long time at high temperature,and has good wear resistance and hydrophobicity,which improves the filter material’s clearness,and enhances the service life and stability of the filter material at high temperature.The filtration efficiency is over 70%,increased by about 40%,the filtration resistance is less than 200 Pa,and the filtration performance is greatly improved.The pore size of the filter material is mostly distributed below 10 μm,the pore size of the surface microporous coating is less than 1 μm,the surface microporous coating is compact,and the cross section forms a porous,multilayered,internally connected microporous structure.PTFE foam coating glass fiber composite filter material of average pore diameter is small,good air permeability,low filter resistance,high filtration efficiency,is a kind of high temperature resistance,wear resistance,easy cleaning of ash,stability,long life and other excellent performance of new compound filter material,suitable for high precision filter and high temperature,super high temperature dust in the industrial flue gas field.